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Microb Ecol

Title:		"Prodigiosin, Violacein, and Volatile Organic Compounds Produced by Widespread Cutaneous Bacteria of Amphibians Can Inhibit Two Batrachochytrium Fungal Pathogens"
Author(s):		Woodhams DC; LaBumbard BC; Barnhart KL; Becker MH; Bletz MC; Escobar LA; Flechas SV; Forman ME; Iannetta AA; Joyce MD; Rabemananjara F; Gratwicke B; Vences M; Minbiole KPC;
Address:		"Biology Department, University of Massachusetts Boston, Boston, MA, 02125, USA. dwoodhams@gmail.com. Biology Department, University of Massachusetts Boston, Boston, MA, 02125, USA. Smithsonian Conservation Biology Institute, National Zoological Park, Washington, DC, USA. Department of Biology and Chemistry, Liberty University, Lynchburg, VA, USA. Zoological Institute, Technische Universitat Braunschweig, 38106, Braunschweig, Germany. School of Sciences, Pontificia Universidad Javeriana, Bogota, AA 56710, Colombia. Department of Biological Sciences, Universidad de los Andes, Bogota, AA 4976, Colombia. Department of Chemistry, Villanova University, Villanova, PA, 19085, USA. Department of Chemistry, University of North Carolina, Chapel Hill, NC, 27514, USA. University of Antananarivo, Antananarivo, Madagascar. Department of Chemistry, Villanova University, Villanova, PA, 19085, USA. kevin.minbiole@villanova.edu"
Journal Title:		Microb Ecol
Year:		2018
Volume:		20171109
Issue:		4
Page Number:		1049 - 1062
DOI:		10.1007/s00248-017-1095-7
ISSN/ISBN:		1432-184X (Electronic) 0095-3628 (Linking)
Abstract:		"Symbiotic bacteria can produce secondary metabolites and volatile compounds that contribute to amphibian skin defense. Some of these symbionts have been used as probiotics to treat or prevent the emerging disease chytridiomycosis. We examined 20 amphibian cutaneous bacteria for the production of prodigiosin or violacein, brightly colored defense compounds that pigment the bacteria and have characteristic spectroscopic properties making them readily detectable, and evaluated the antifungal activity of these compounds. We detected violacein from all six isolates of Janthinobacterium lividum on frogs from the USA, Switzerland, and on captive frogs originally from Panama. We detected prodigiosin from five isolates of Serratia plymuthica or S. marcescens, but not from four isolates of S. fonticola or S. liquefaciens. All J. lividum isolates produced violacein when visibly purple, while prodigiosin was only detected on visibly red Serratia isolates. When applied to cultures of chytrid fungi Batrachochytrium dendrobatidis (Bd) and B. salamandrivorans (Bsal), prodigiosin caused significant growth inhibition, with minimal inhibitory concentrations (MIC) of 10 and 50 muM, respectively. Violacein showed a MIC of 15 muM against both fungi and was slightly more active against Bsal than Bd at lower concentrations. Although neither violacein nor prodigiosin showed aerosol activity and is not considered a volatile organic compound (VOC), J. lividum and several Serratia isolates did produce antifungal VOCs. White Serratia isolates with undetectable prodigiosin levels could still inhibit Bd growth indicating additional antifungal compounds in their chemical arsenals. Similarly, J. lividum can produce antifungal compounds such as indole-3-carboxaldehyde in addition to violacein, and isolates are not always purple, or turn purple under certain growth conditions. When Serratia isolates were grown in the presence of cell-free supernatant (CFS) from the fungi, CFS from Bd inhibited growth of the prodigiosin-producing isolates, perhaps indicative of an evolutionary arms race; Bsal CFS did not inhibit bacterial growth. In contrast, growth of one J. lividum isolate was facilitated by CFS from both fungi. Isolates that grow and continue to produce antifungal compounds in the presence of pathogens may represent promising probiotics for amphibians infected or at risk of chytridiomycosis. In a global analysis, 89% of tested Serratia isolates and 82% of J. lividum isolates were capable of inhibiting Bd and these have been reported from anurans and caudates from five continents, indicating their widespread distribution and potential for host benefit"
Keywords:		Animals Antifungal Agents/pharmacology Anura/microbiology Bacteria/classification/isolation & purification/*metabolism Biological Control Agents/antagonists & inhibitors Chytridiomycota/*drug effects/growth & development/pathogenicity Indoles/*antagonists;
Notes:		"MedlineWoodhams, Douglas C LaBumbard, Brandon C Barnhart, Kelly L Becker, Matthew H Bletz, Molly C Escobar, Laura A Flechas, Sandra V Forman, Megan E Iannetta, Anthony A Joyce, Maureen D Rabemananjara, Falitiana Gratwicke, Brian Vences, Miguel Minbiole, Kevin P C eng DEB-1136662/Division of Environmental Biology/ 2017/11/10 Microb Ecol. 2018 May; 75(4):1049-1062. doi: 10.1007/s00248-017-1095-7. Epub 2017 Nov 9"